Merge pull request fool2fish#30 from dxhj/master

Add some source file for exercise 3.5

ch03/3.5/src/lex.l

@@ -0,0 +1,48 @@
+%{
+/* definitions of manifest constants
+LT, LE, EQ, NE, GT, GE,
+IF, THEN, ELSE, ID, NUMBER, RELOP */
+%}
+/* regular definitions */
+delim   [ \t\n]
+ws      {delim}+
+
+/* Exercise 3.5.1 - c) We can allow the underscore here, but I think it's better in the ID definition. */
+letter  [A-Za-z]
+digit   [0-9]
+
+/* Exercise 3.5.1 - c) */
+id      {letter}({letter}|{digit}|_)*
+
+number  {digit}+(\.{digit}+)?(E[+-]?{digit }+)?
+doubleq \"
+
+%%
+{ws} {/* no action and no return */}
+if   {return (IF); }
+while { return (WHILE); /* Exercise 3.5.1 - a) */ }
+then {return (THEN); }
+else {return (ELSE) ; }
+{id} {yylval = (int) installID(); return (ID); }
+{doubleq}.*{doubleq} { yylval = (int) installString(); return (STRING); /* Exercise 3.5.1 - d) */}
+{number} {yylval = (int) installNum(); return (NUMBER); }
+"<" {yylval = LT; return (RELOP); }
+"<=" {yylval = LE; return (RELOP);}
+"==" {yylval = EQ; return (RELOP); /* Exercise 3.5.1 - b) */ }
+"!=" {yylval = NE; return (RELOP ); /* Exercise 3.5.1 - b) */ }
+">" {yylval = GT; return (RELOP); }
+">=" {yylval = GE; return (RELOP); }
+
+%%
+
+int installID() { /* function to install the lexeme, whose first character is pointed to bu yytext,
+and whose length is yyleng, into the symbol table and return a pointer thereto */
+}
+
+int installNum() { /* similar to installID, but puts numerical constants into a seperate table */ 
+}
+
+int installString() {
+/* ... */
+}
+

ch03/3.5/src/lex2.l

@@ -0,0 +1,35 @@
+%{
+%}
+
+delim 	[ \t]
+ws 			{delim}+
+letter 	[a-zA-Z]
+word   	{letter}+
+
+%%
+{ws} { printf("%s", yytext); }
+{word} { 
+	if (starts_vowel(yytext)) 
+		printf("%say", yytext);
+	else
+		printf("%s%cay", yytext+1, yytext[0]);
+. { printf("%s", yytext); }
+%%
+
+int starts_vowel(char *c){
+	switch(c[0]){
+		case 'a':
+		case 'e':
+		case 'i':
+		case 'o':
+		case 'u':
+		case 'A':
+		case 'E':
+		case 'I':
+		case 'O':
+		case 'U':
+			return 1;
+		default:
+			return 0;
+ 	}
+}

ch03/3.5/src/lex3.l

@@ -0,0 +1,40 @@
+%{
+
+%}
+
+letter 	[a-zA-Z]
+digit 	[0-9]
+
+/* [w-W][h-H][i-I][l-L][e-E] works too. */
+while 	(?i:while)
+
+from	(?i:from)
+select	(?i:select)
+id	{letter}({letter}|{digit})*
+
+%%
+{while} 	{ printf("WHILE KEYWORD"); return (WHILE); }
+{from} 		{ printf("FROM KEYWORD"); return (FROM); }
+{select}	{ printf("SELECT KEYWORD"); return (SELECT); }
+{id}		{ printf("ID"); yytext = lowercase(yytext); yylval = (int) installID(); return (ID); }	
+%%
+
+
+int installID(){
+	/* We've to convert the lexeme to lowercase and install it 
+
+	example:
+		yytext: foO
+		yytext = lowercase(yytext)
+		installID()
+
+		yytext: Strstr
+		yytext = lowercase(yytext)
+		yylval = (int) installID()
+		
+		yytext: strstr (already exists in the symbol table)
+		yytext = lowercase(yytext)
+		yylval = (int) installID()
+
+	*/
+}